Sealed and thermally insulating tank

Abstract

A sealed and thermally insulating tank for transporting and/or storing liquefied natural gas includes a load-bearing structure and a storage structure surrounded by the load-bearing structure. The storage structure includes a first portion and a second portion that are sealed with respect to one another, the first portion and the second portion extending in one and the same plane which is parallel to the load-bearing structure. The tank includes a closure device arranged in the thickness of the storage structure. The closure device includes a first closure member and a second closure member that cooperate with one another to separate the first portion from second portion. One of the closure members includes a first part and a second part that extend in intersecting planes. One of the parts is connected to one of the portions by a fastening device that is arranged in the thickness of the storage structure.

The invention claimed is: 
     
         1 . A sealed and thermally insulating tank for transport and/or storage of liquefied natural gas, comprising:
 at least a supporting structure and a storage structure surrounded by the supporting structure, the storage structure comprising at least a first portion and a second portion which are sealed relative to one another, the first portion and the second portion extending at least partially in the same plane parallel to the supporting structure, the storage structure having a thickness from the outside toward the inside of the tank in a direction perpendicular to the plane of the supporting structure, the tank comprising a closure device arranged at least partially in the thickness of the storage structure, the closure device comprising at least a first closure member and a second closure member configured to interact with one another in such a way as to separate the first portion from the second portion, at least one of the closure members comprising a first part and a second part extending in secant planes, wherein at least one of the parts of one and/or the other of the closure members is connected to at least one of the portions by a securing device arranged in the thickness of the storage structure, and wherein the first closing member and the second closing member have an L shaped profile seen in a section plane passing through the closing device.   
     
     
         2 . The tank as claimed in  claim 1 , wherein at least one of the closure members is secured to the other closure member by at least one weld bead. 
     
     
         3 . The tank as claimed in  claim 1 , wherein the first closure member and/or the second closure member of the closure device are elastically deformable. 
     
     
         4 . The tank as claimed in  claim 1 , wherein one of the closure members is connected to at least one of the portions by the securing device arranged in the thickness of the storage structure, the other closure member being connected to the supporting structure. 
     
     
         5 . The tank as claimed in  claim 4 , wherein the first portion comprises a secondary space and a primary space, the secondary space comprising, successively in the thickness direction from the outside toward the inside of the tank, a secondary thermally insulating barrier adapted to be in contact with the supporting structure and a secondary sealing membrane resting on the secondary thermally insulating barrier, the securing device extending at least partially into the secondary thermally insulating barrier, the primary space comprising, successively in the thickness direction from the outside toward the inside of the tank, a primary thermally insulating barrier which rests on the secondary sealing membrane and a primary sealing membrane resting on the primary thermally insulating barrier and configured to be in contact with a fluid contained in the tank, the second portion comprising a thermally insulating wall adapted to be in contact with the supporting structure and an impermeable membrane resting on the thermally insulating wall and configured to be in contact with the fluid contained in the tank. 
     
     
         6 . The tank as claimed in  claim 5 , wherein the secondary space comprises a securing plate arranged between the secondary thermally insulating barrier and the primary space, the first part of the first closure member being connected to the securing plate by at least one weld bead, the second part of the first closure member being connected to the secondary thermally insulating barrier by the securing device arranged in the thickness of the storage structure. 
     
     
         7 . The tank as claimed in  claim 5 , wherein the supporting structure comprises an insert, the first part of the second closure member being connected to the insert by at least one weld bead, the second part of the second closure member being connected to the secondary thermally insulating barrier by the securing device arranged in the thickness of the storage structure. 
     
     
         8 . The tank as claimed in  claim 6 , wherein at least the secondary space comprises at least one thermally insulating self-supporting panel having an internal face oriented toward the inside of the tank, an external face oriented toward the outside of the tank, and a thickness face extending between the internal face and the external face of the self-supporting panel, the self-supporting panel of the secondary space adjacent to the first closure member comprising a chamfer connecting the internal face and the thickness face of the self-supporting panel. 
     
     
         9 . The tank as claimed in  claim 8 , wherein the thickness face of the self-supporting panel comprises a plywood panel which receives the securing device. 
     
     
         10 . The tank as claimed in  claim 8 , wherein the first closure member comprises a bent part connecting the first part to the second part of the first closure member, the first closure member being positioned against the internal face and the thickness face of the self-supporting panel of the secondary space such that the bent part of the first closure member is arranged in line with the chamfer on the self-supporting panel. 
     
     
         11 . A transport and/or storage unit comprising:
 at least one of the tank as claimed in  claim 1 , wherein the transport and/or storage unit is a ship, a barge, a reliquefaction unit, gasification unit, an onshore structure or a gravity platform.   
     
     
         12 . A method for assembling a junction zone between the first portion and the second portion of the tank as claimed in  claim 5 , the method comprising fitting the secondary thermally insulating barrier against the supporting structure. 
     
     
         13 . The method for assembling the junction zone as claimed in  claim 12 , further comprising securing the second part of the first closure member or of the second closure member in a thickness of the secondary thermally insulating barrier by the securing device. 
     
     
         14 . The method for assembling the junction zone as claimed in  claim 13 , wherein the secondary thermally insulating barrier comprises a securing plate, and the method further comprises securing the first part of the first closure member to the secondary thermally insulating barrier at the securing plate by a weld bead. 
     
     
         15 . The method for assembling the junction zone as claimed in  claim 14 , wherein the supporting structure comprises an insert, and the method comprises securing the second part of the second closure member to the second part of the first closure member by a weld bead, and securing the first part of the second closure member to the insert of the supporting structure by another weld bead. 
     
     
         16 . The method for assembling the junction zone as claimed in  claim 15 , further comprising fitting the secondary sealing membrane against the secondary thermally insulating barrier. 
     
     
         17 . The method for assembling the junction zone as claimed in  claim 16 , further comprising fitting the primary thermally insulating barrier against the secondary space, part of the primary thermally insulating barrier partially covering the first part of the first closure member, and the thermally insulating wall is fitted against the supporting structure at least in the main plane of extension of the secondary space, part of the thermally insulating wall being arranged in line with the first part of the second closure member along the thickness. 
     
     
         18 . The method for assembling the junction zone as claimed in  claim 17 , further comprising fitting the primary sealing membrane and the impermeable membrane against the primary thermally insulating barrier and against the thermally insulating wall, respectively, the primary sealing membrane and the impermeable membrane extending in a common plane.